diff --git a/src/librustc_mir/borrow_check/type_check/input_output.rs b/src/librustc_mir/borrow_check/type_check/input_output.rs
index edd2dc3..8cebd36 100644
--- a/src/librustc_mir/borrow_check/type_check/input_output.rs
+++ b/src/librustc_mir/borrow_check/type_check/input_output.rs
@@ -122,7 +122,7 @@
         if let Err(terr) = self.eq_opaque_type_and_type(
             mir_output_ty,
             normalized_output_ty,
-            self.mir_def_id.to_def_id(),
+            self.mir_def_id,
             Locations::All(output_span),
             ConstraintCategory::BoringNoLocation,
         ) {
@@ -145,7 +145,7 @@
             if let Err(err) = self.eq_opaque_type_and_type(
                 mir_output_ty,
                 user_provided_output_ty,
-                self.mir_def_id.to_def_id(),
+                self.mir_def_id,
                 Locations::All(output_span),
                 ConstraintCategory::BoringNoLocation,
             ) {
diff --git a/src/librustc_mir/borrow_check/type_check/mod.rs b/src/librustc_mir/borrow_check/type_check/mod.rs
index 0e35caf..3532b6d 100644
--- a/src/librustc_mir/borrow_check/type_check/mod.rs
+++ b/src/librustc_mir/borrow_check/type_check/mod.rs
@@ -1144,7 +1144,8 @@
                 // When you have `let x: impl Foo = ...` in a closure,
                 // the resulting inferend values are stored with the
                 // def-id of the base function.
-                let parent_def_id = self.tcx().closure_base_def_id(self.mir_def_id.to_def_id());
+                let parent_def_id =
+                    self.tcx().closure_base_def_id(self.mir_def_id.to_def_id()).expect_local();
                 return self.eq_opaque_type_and_type(sub, sup, parent_def_id, locations, category);
             } else {
                 return Err(terr);
@@ -1208,7 +1209,7 @@
         &mut self,
         revealed_ty: Ty<'tcx>,
         anon_ty: Ty<'tcx>,
-        anon_owner_def_id: DefId,
+        anon_owner_def_id: LocalDefId,
         locations: Locations,
         category: ConstraintCategory,
     ) -> Fallible<()> {
@@ -1238,8 +1239,7 @@
         let tcx = infcx.tcx;
         let param_env = self.param_env;
         let body = self.body;
-        let concrete_opaque_types =
-            &tcx.typeck_tables_of(anon_owner_def_id.expect_local()).concrete_opaque_types;
+        let concrete_opaque_types = &tcx.typeck_tables_of(anon_owner_def_id).concrete_opaque_types;
         let mut opaque_type_values = Vec::new();
 
         debug!("eq_opaque_type_and_type: mir_def_id={:?}", self.mir_def_id);
diff --git a/src/librustc_mir/const_eval/eval_queries.rs b/src/librustc_mir/const_eval/eval_queries.rs
index d62300b..75067ff 100644
--- a/src/librustc_mir/const_eval/eval_queries.rs
+++ b/src/librustc_mir/const_eval/eval_queries.rs
@@ -334,9 +334,9 @@
                 }
 
                 v
-            } else if def_id.is_local() {
+            } else if let Some(def_id) = def_id.as_local() {
                 // constant defined in this crate, we can figure out a lint level!
-                match tcx.def_kind(def_id) {
+                match tcx.def_kind(def_id.to_def_id()) {
                     // constants never produce a hard error at the definition site. Anything else is
                     // a backwards compatibility hazard (and will break old versions of winapi for
                     // sure)
@@ -346,7 +346,7 @@
                     // validation thus preventing such a hard error from being a backwards
                     // compatibility hazard
                     DefKind::Const | DefKind::AssocConst => {
-                        let hir_id = tcx.hir().as_local_hir_id(def_id.expect_local());
+                        let hir_id = tcx.hir().as_local_hir_id(def_id);
                         err.report_as_lint(
                             tcx.at(tcx.def_span(def_id)),
                             "any use of this value will cause an error",
@@ -369,7 +369,7 @@
                                 err.report_as_lint(
                                     tcx.at(span),
                                     "reaching this expression at runtime will panic or abort",
-                                    tcx.hir().as_local_hir_id(def_id.expect_local()),
+                                    tcx.hir().as_local_hir_id(def_id),
                                     Some(err.span),
                                 )
                             }
diff --git a/src/librustc_mir/transform/check_consts/mod.rs b/src/librustc_mir/transform/check_consts/mod.rs
index e4aa88e..81c1b0b 100644
--- a/src/librustc_mir/transform/check_consts/mod.rs
+++ b/src/librustc_mir/transform/check_consts/mod.rs
@@ -22,7 +22,7 @@
 pub struct ConstCx<'mir, 'tcx> {
     pub body: &'mir mir::Body<'tcx>,
     pub tcx: TyCtxt<'tcx>,
-    pub def_id: DefId,
+    pub def_id: LocalDefId,
     pub param_env: ty::ParamEnv<'tcx>,
     pub const_kind: Option<hir::ConstContext>,
 }
@@ -40,7 +40,7 @@
         param_env: ty::ParamEnv<'tcx>,
     ) -> Self {
         let const_kind = tcx.hir().body_const_context(def_id);
-        ConstCx { body, tcx, def_id: def_id.to_def_id(), param_env, const_kind }
+        ConstCx { body, tcx, def_id: def_id, param_env, const_kind }
     }
 
     /// Returns the kind of const context this `Item` represents (`const`, `static`, etc.).
diff --git a/src/librustc_mir/transform/check_consts/post_drop_elaboration.rs b/src/librustc_mir/transform/check_consts/post_drop_elaboration.rs
index 1fd907f..55075b3 100644
--- a/src/librustc_mir/transform/check_consts/post_drop_elaboration.rs
+++ b/src/librustc_mir/transform/check_consts/post_drop_elaboration.rs
@@ -29,13 +29,7 @@
         return;
     }
 
-    let ccx = ConstCx {
-        body,
-        tcx,
-        def_id: def_id.to_def_id(),
-        const_kind,
-        param_env: tcx.param_env(def_id),
-    };
+    let ccx = ConstCx { body, tcx, def_id, const_kind, param_env: tcx.param_env(def_id) };
 
     let mut visitor = CheckLiveDrops { ccx: &ccx, qualifs: Qualifs::default() };
 
diff --git a/src/librustc_mir/transform/check_consts/qualifs.rs b/src/librustc_mir/transform/check_consts/qualifs.rs
index e2893e8..3dddd9c 100644
--- a/src/librustc_mir/transform/check_consts/qualifs.rs
+++ b/src/librustc_mir/transform/check_consts/qualifs.rs
@@ -126,7 +126,7 @@
         // because that component may be part of an enum variant (e.g.,
         // `Option::<NonStructuralMatchTy>::Some`), in which case some values of this type may be
         // structural-match (`Option::None`).
-        let id = cx.tcx.hir().local_def_id_to_hir_id(cx.def_id.as_local().unwrap());
+        let id = cx.tcx.hir().local_def_id_to_hir_id(cx.def_id);
         traits::search_for_structural_match_violation(id, cx.body.span, cx.tcx, ty).is_some()
     }
 
diff --git a/src/librustc_mir/transform/check_consts/validation.rs b/src/librustc_mir/transform/check_consts/validation.rs
index f00fc96..5cb161e 100644
--- a/src/librustc_mir/transform/check_consts/validation.rs
+++ b/src/librustc_mir/transform/check_consts/validation.rs
@@ -56,7 +56,7 @@
             // without breaking stable code?
             MaybeMutBorrowedLocals::mut_borrows_only(tcx, &body, param_env)
                 .unsound_ignore_borrow_on_drop()
-                .into_engine(tcx, &body, def_id)
+                .into_engine(tcx, &body, def_id.to_def_id())
                 .iterate_to_fixpoint()
                 .into_results_cursor(&body)
         });
@@ -83,7 +83,7 @@
             let ConstCx { tcx, body, def_id, .. } = *ccx;
 
             FlowSensitiveAnalysis::new(NeedsDrop, ccx)
-                .into_engine(tcx, &body, def_id)
+                .into_engine(tcx, &body, def_id.to_def_id())
                 .iterate_to_fixpoint()
                 .into_results_cursor(&body)
         });
@@ -110,7 +110,7 @@
             let ConstCx { tcx, body, def_id, .. } = *ccx;
 
             FlowSensitiveAnalysis::new(HasMutInterior, ccx)
-                .into_engine(tcx, &body, def_id)
+                .into_engine(tcx, &body, def_id.to_def_id())
                 .iterate_to_fixpoint()
                 .into_results_cursor(&body)
         });
@@ -153,7 +153,7 @@
 
             hir::ConstContext::Const | hir::ConstContext::Static(_) => {
                 let mut cursor = FlowSensitiveAnalysis::new(CustomEq, ccx)
-                    .into_engine(ccx.tcx, &ccx.body, ccx.def_id)
+                    .into_engine(ccx.tcx, &ccx.body, ccx.def_id.to_def_id())
                     .iterate_to_fixpoint()
                     .into_results_cursor(&ccx.body);
 
@@ -195,13 +195,13 @@
         let ConstCx { tcx, body, def_id, const_kind, .. } = *self.ccx;
 
         let use_min_const_fn_checks = (const_kind == Some(hir::ConstContext::ConstFn)
-            && crate::const_eval::is_min_const_fn(tcx, def_id))
+            && crate::const_eval::is_min_const_fn(tcx, def_id.to_def_id()))
             && !tcx.sess.opts.debugging_opts.unleash_the_miri_inside_of_you;
 
         if use_min_const_fn_checks {
             // Enforce `min_const_fn` for stable `const fn`s.
             use crate::transform::qualify_min_const_fn::is_min_const_fn;
-            if let Err((span, err)) = is_min_const_fn(tcx, def_id, &body) {
+            if let Err((span, err)) = is_min_const_fn(tcx, def_id.to_def_id(), &body) {
                 error_min_const_fn_violation(tcx, span, err);
                 return;
             }
@@ -212,10 +212,10 @@
         // Ensure that the end result is `Sync` in a non-thread local `static`.
         let should_check_for_sync = const_kind
             == Some(hir::ConstContext::Static(hir::Mutability::Not))
-            && !tcx.is_thread_local_static(def_id);
+            && !tcx.is_thread_local_static(def_id.to_def_id());
 
         if should_check_for_sync {
-            let hir_id = tcx.hir().as_local_hir_id(def_id.expect_local());
+            let hir_id = tcx.hir().as_local_hir_id(def_id);
             check_return_ty_is_sync(tcx, &body, hir_id);
         }
     }
@@ -535,7 +535,7 @@
                     // `#[allow_internal_unstable]`.
                     use crate::transform::qualify_min_const_fn::lib_feature_allowed;
                     if !self.span.allows_unstable(feature)
-                        && !lib_feature_allowed(self.tcx, self.def_id, feature)
+                        && !lib_feature_allowed(self.tcx, self.def_id.to_def_id(), feature)
                     {
                         self.check_op(ops::FnCallUnstable(def_id, feature));
                     }
diff --git a/src/librustc_mir/transform/mod.rs b/src/librustc_mir/transform/mod.rs
index 8ca240d..14c3093 100644
--- a/src/librustc_mir/transform/mod.rs
+++ b/src/librustc_mir/transform/mod.rs
@@ -203,7 +203,8 @@
 }
 
 fn mir_const_qualif(tcx: TyCtxt<'_>, def_id: DefId) -> ConstQualifs {
-    let const_kind = tcx.hir().body_const_context(def_id.expect_local());
+    let def_id = def_id.expect_local();
+    let const_kind = tcx.hir().body_const_context(def_id);
 
     // No need to const-check a non-const `fn`.
     if const_kind.is_none() {
@@ -214,7 +215,7 @@
     // cannot yet be stolen), because `mir_validated()`, which steals
     // from `mir_const(), forces this query to execute before
     // performing the steal.
-    let body = &tcx.mir_const(def_id).borrow();
+    let body = &tcx.mir_const(def_id.to_def_id()).borrow();
 
     if body.return_ty().references_error() {
         tcx.sess.delay_span_bug(body.span, "mir_const_qualif: MIR had errors");
diff --git a/src/librustc_mir/transform/promote_consts.rs b/src/librustc_mir/transform/promote_consts.rs
index bd7ebaa..5aa6722 100644
--- a/src/librustc_mir/transform/promote_consts.rs
+++ b/src/librustc_mir/transform/promote_consts.rs
@@ -60,15 +60,16 @@
             return;
         }
 
-        let def_id = src.def_id();
+        let def_id = src.def_id().expect_local();
 
         let mut rpo = traversal::reverse_postorder(body);
-        let ccx = ConstCx::new(tcx, def_id.expect_local(), body);
+        let ccx = ConstCx::new(tcx, def_id, body);
         let (temps, all_candidates) = collect_temps_and_candidates(&ccx, &mut rpo);
 
         let promotable_candidates = validate_candidates(&ccx, &temps, &all_candidates);
 
-        let promoted = promote_candidates(def_id, body, tcx, temps, promotable_candidates);
+        let promoted =
+            promote_candidates(def_id.to_def_id(), body, tcx, temps, promotable_candidates);
         self.promoted_fragments.set(promoted);
     }
 }
@@ -724,7 +725,7 @@
             ty::FnDef(def_id, _) => {
                 is_const_fn(self.tcx, def_id)
                     || is_unstable_const_fn(self.tcx, def_id).is_some()
-                    || is_lang_panic_fn(self.tcx, self.def_id)
+                    || is_lang_panic_fn(self.tcx, self.def_id.to_def_id())
             }
             _ => false,
         };
diff --git a/src/librustc_trait_selection/opaque_types.rs b/src/librustc_trait_selection/opaque_types.rs
index ce478de..b605318 100644
--- a/src/librustc_trait_selection/opaque_types.rs
+++ b/src/librustc_trait_selection/opaque_types.rs
@@ -108,7 +108,7 @@
 pub trait InferCtxtExt<'tcx> {
     fn instantiate_opaque_types<T: TypeFoldable<'tcx>>(
         &self,
-        parent_def_id: DefId,
+        parent_def_id: LocalDefId,
         body_id: hir::HirId,
         param_env: ty::ParamEnv<'tcx>,
         value: &T,
@@ -184,7 +184,7 @@
     /// - `value_span` -- the span where the value came from, used in error reporting
     fn instantiate_opaque_types<T: TypeFoldable<'tcx>>(
         &self,
-        parent_def_id: DefId,
+        parent_def_id: LocalDefId,
         body_id: hir::HirId,
         param_env: ty::ParamEnv<'tcx>,
         value: &T,
@@ -986,7 +986,7 @@
 
 struct Instantiator<'a, 'tcx> {
     infcx: &'a InferCtxt<'a, 'tcx>,
-    parent_def_id: DefId,
+    parent_def_id: LocalDefId,
     body_id: hir::HirId,
     param_env: ty::ParamEnv<'tcx>,
     value_span: Span,
@@ -1043,8 +1043,7 @@
                         let parent_def_id = self.parent_def_id;
                         let def_scope_default = || {
                             let opaque_parent_hir_id = tcx.hir().get_parent_item(opaque_hir_id);
-                            parent_def_id
-                                == tcx.hir().local_def_id(opaque_parent_hir_id).to_def_id()
+                            parent_def_id == tcx.hir().local_def_id(opaque_parent_hir_id)
                         };
                         let (in_definition_scope, origin) = match tcx.hir().find(opaque_hir_id) {
                             Some(Node::Item(item)) => match item.kind {
@@ -1053,18 +1052,14 @@
                                     impl_trait_fn: Some(parent),
                                     origin,
                                     ..
-                                }) => (parent == self.parent_def_id, origin),
+                                }) => (parent == self.parent_def_id.to_def_id(), origin),
                                 // Named `type Foo = impl Bar;`
                                 hir::ItemKind::OpaqueTy(hir::OpaqueTy {
                                     impl_trait_fn: None,
                                     origin,
                                     ..
                                 }) => (
-                                    may_define_opaque_type(
-                                        tcx,
-                                        self.parent_def_id.expect_local(),
-                                        opaque_hir_id,
-                                    ),
+                                    may_define_opaque_type(tcx, self.parent_def_id, opaque_hir_id),
                                     origin,
                                 ),
                                 _ => (def_scope_default(), hir::OpaqueTyOrigin::Misc),
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index 58fd0f9..e564b01 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -1321,8 +1321,8 @@
         fcx.resume_yield_tys = Some((resume_ty, yield_ty));
     }
 
-    let outer_def_id = tcx.closure_base_def_id(hir.local_def_id(fn_id).to_def_id());
-    let outer_hir_id = hir.as_local_hir_id(outer_def_id.expect_local());
+    let outer_def_id = tcx.closure_base_def_id(hir.local_def_id(fn_id).to_def_id()).expect_local();
+    let outer_hir_id = hir.as_local_hir_id(outer_def_id);
     GatherLocalsVisitor { fcx: &fcx, parent_id: outer_hir_id }.visit_body(body);
 
     // C-variadic fns also have a `VaList` input that's not listed in `fn_sig`
@@ -3427,7 +3427,7 @@
 
         let (value, opaque_type_map) =
             self.register_infer_ok_obligations(self.instantiate_opaque_types(
-                parent_def_id.to_def_id(),
+                parent_def_id,
                 self.body_id,
                 self.param_env,
                 value,